Electronics rack cooling duct

ABSTRACT

A chilled-air duct for providing chilled air from an under-floor plenum space to electronics modules disposed in a rack or cabinet. The duct has a generally right triangular profile formed by a substantially vertical forward wall and a sloping rear wall. A single vent extends from a sidewall of the duct and alongside the forward wall to direct chilled air flowing through the duct to a space in front of the electronics modules. The vent extends from near a base of the duct to a top wall thereof. Air-blocks can be disposed in the vent opening to customize airflow from the duct. Flow and distribution of chilled air from the vent is at least partially equalized by the profile of the duct. The duct is freestanding and can be disposed alongside a rack or within a cabinet between a mounting frame and a sidewall thereof.

BACKGROUND

A major concern for data centers and other facilities that house racked electronic components or modules, such as servers, blades, routers, data storage devices, audio/video equipment, and telecommunications equipment, among other electronic and computing devices, is cooling of the modules. The modules are typically installed in a vertically stacked orientation in a rack. The racks are aligned in rows to form cold aisles and hot aisles; the modules face the cold aisles and face away from the hot aisles. Chilled air is pumped into the cold aisles, typically from a plenum space beneath a raised floor of the room and through perforated tiles disposed in the floor of the cold aisles. The chilled air is drawn from the cold aisle toward the front of the racks to the modules mounted therein. Fans disposed within the modules draw the chilled air through the respective module to cool the electronics therein and to exhaust the now warm air from the rear of the module and into the hot aisle. The warm air is then drawn away from the hot aisle, such as via ducts disposed above the hot aisle for treatment or venting from the room.

Such cooling systems present a variety of drawbacks. The distribution of the chilled air to the modules is random and inefficient. Very little airflow is achieved by provision of the chilled air through the floor tiles, which results in uneven distribution of the chilled air. Additionally, a large amount of the chilled air passes over the top of the racks/cabinets to the warm air venting system and is thus wasted. The use of cold aisles also requires additional floor space in the cold aisle for provision of a sufficient amount of chilled air to the racks/cabinets thus decreasing the number of modules that can be disposed in a given room.

A variety of attempts have been made to increase the cooling efficiency. For example, U.S. Pat. No. 6,516,954 to Broome describes a rack unit that is used in pairs for mounting electronic equipment therebetween. Each rack unit forms a hollow vertically extending support structure. The interior of the hollow is partitioned to form a front and a rear section. Chilled air is forced through the front section and passes through vents along the front of the rack unit. The vents comprise holes through and spaced vertically along the front face of the rack unit. The rear section is configured to receive and organize cables associated with the electronic modules mounted on the rack unit.

U.S. Pat. No. 7,226,353 to Bettridge et al. describes a cabinet with a rack mounted therein for housing electronics modules. An inlet fan is provided in a plenum space of the cabinet at the base of the rack and is in fluid communication with one or more ducts that extend along the sides of the cabinet between the sidewall thereof and the rack. The duct includes a plurality of discharge ports along a side thereof and positioned in a space between a front door of the cabinet and the front faces of the electronics modules. The discharge ports are adjustable to direct airflow and can be closed off when no module is mounted adjacent to the port. Cool air is drawn from the cold aisle into the plenum space and forced through the ducts to the front of the electronics modules.

U.S. Pat. No. 7,443,647 to Hanlon discloses a replacement panel for a wall panel of a computer rack enclosure. The panel has a hollow interior with a partition disposed therein to divide the panel into a pair of vertically oriented ducts. The partition includes perforations such that cool air drawn into a first duct is evenly dispersed into the second duct. The cool air is then forced out of vents in the second duct toward the front of modules mounted in the rack enclosure. A fan is associated with the first duct to draw cool air into the first duct from a cold aisle.

U.S. Pat. No. 7,907,402 to Caveney discloses an electronics cabinet with ducts extending along and within sides thereof. The ducts receive chilled air from beneath the floor and include vents located adjacent a front edge between a front wall of the cabinet and front faces of the electronic equipment disposed therein for dispersing the cooled air to the electronics equipment. A horizontal shelf is included to divide the cabinet into a top and a bottom zone to further control cooling of the equipment.

However, prior attempts, like those discussed above, employ complex modules, and configurations that are not easily installed on existing rack and cabinet systems. A need remains for a simple cooling apparatus that can be installed on new rack and cabinet enclosures and retrofitted to existing enclosures. A need also exists for a cooling apparatus that efficiently provides chilled air to rack and cabinet mounted modules and that is adaptable to provide chilled air only where needed within the rack or cabinet.

SUMMARY

Embodiments of the invention are defined by the claims below, not this summary. A high-level overview of various aspects of the invention are provided here for that reason, to provide an overview of the disclosure, and to introduce a selection of concepts that are further described in the Detailed Description section below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in isolation to determine the scope of the claimed subject matter. In brief, this disclosure describes, among other things, a chilled-air duct for providing chilled air from an under-floor plenum space to electronics modules mounted in a rack or cabinet enclosure.

In an embodiment, the chilled-air duct comprises a free-standing component that is disposable in a cabinet enclosure or associated with a rack mounting system and fits within an existing space alongside electrical modules mounted in the cabinet or rack. A side profile of the duct has a generally right-triangular shape with an apex near the top and front of the cabinet or rack and a base nearest the floor that extends along substantially the full length of the side of the cabinet/rack. A single vent extends parallel to the front of the cabinet/rack and along substantially the full height of the duct. The base of the duct is disposed over an opening in the floor to receive a flow of chilled air from beneath the floor.

The duct thus directs chilled air from beneath the floor directly to the front of electrical modules mounted in the cabinet/rack. The tapered side profile of the duct aids to provide a desired distribution and/or equalization of airflow over the height of the duct such that modules mounted in the cabinet/rack receive sufficient cooling no matter their vertical position therein.

One or more air-blocks can be disposed on the vent to block airflow to areas in which no module is mounted or no cooling is needed. The length of the air-blocks is infinitely selectable by cutting the air-blocks to length to accommodate any desired amount of space within the cabinet/rack that is not to be cooled.

DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention are described in detail below with reference to the attached drawing figures, and wherein:

FIG. 1 is a perspective view of a chilled-air duct associated with a rack holding a plurality of electronics modules and depicted in accordance with an embodiment of the invention, the rack being depicted with side panels and doors removed;

FIG. 2 is a first side elevational view of the chilled-air duct of FIG. 1;

FIG. 3 is a second side elevational view of the chilled-air duct of FIG. 1;

FIG. 4 is a front side elevational view of the chilled-air duct of FIG. 1;

FIG. 5 is a back side elevational view of the chilled-air duct of FIG. 1;

FIG. 6 is a top plan view of the chilled-air duct of FIG. 1;

FIG. 7 is a bottom plan view of the chilled-air duct of FIG. 1;

FIG. 8 is a partial perspective view of the base of the chilled-air duct of FIG. 1 depicting flow of chilled air from a plenum space beneath a floor through the duct in accordance with an embodiment of the invention;

FIG. 9 is a partial perspective view of a top portion of the chilled-air duct of FIG. 1 with an air-block installed in the vent depicted in accordance with an embodiment of the invention;

FIG. 10A is a top partial perspective view of another chilled-air duct with a contoured vent depicted in accordance with an embodiment of the invention;

FIG. 10B is a top partial perspective view of a chilled-air duct without a vent extending from an inner sidewall thereof depicted in accordance with an embodiment of the invention:

FIG. 10C is a top partial perspective view of chilled-air duct having detents disposed in a front wall and a side vent wall for retaining an air-block in the vent depicted in accordance with an embodiment of the invention;

FIGS. 10D-E are side elevational views of chilled-air ducts having rear walls with varied contours or configurations depicted in accordance with embodiments of the invention;

FIG. 10F is a side elevational view of a chilled-air duct having a flange extending through a raised floor to access an under floor plenum space depicted in accordance with an embodiment of the invention;

FIGS. 11A-D are perspective views of air-block members depicted in accordance with embodiments of the invention.

DETAILED DESCRIPTION

The subject matter of select embodiments of the invention is described with specificity herein to meet statutory requirements. But the description itself is not intended to necessarily limit the scope of claims. Rather, the claimed subject matter might be embodied in other ways to include different components, steps, or combinations thereof similar to the ones described in this document, in conjunction with other present or future technologies. Terms should not be interpreted as implying any particular order among or between various steps herein disclosed unless and except when the order of individual steps is explicitly described.

With reference to FIGS. 1-9, a chilled-air duct 10 is described in accordance with an embodiment of the invention. The chilled-air duct 10 is configured for use with both rack- and cabinet-style electronics mounting systems known in the art, such as a rack 12 depicted in FIG. 1. Both rack- and cabinet-style mounting systems include a mounting frame 14 on which electronics components or modules 16 are disposed in a vertically stacked orientation. The mounting frame 14 can be configured in accordance with known standards or as desired for a particular application. For example, the mounting frame 14 can be configured as a standard 19-inch rack, a 23-inch rack, or other variation and can include a two-post or four-post configuration, among others. The primary distinction between rack- and cabinet-style mounting systems is the inclusion of exterior panels (such as the panel 18) and/or doors that are attached to an external frame 20 and enclose the mounting frame 14 and modules 16 mounted therein. As such, as used hereinafter, the rack 12 is intended to refer to both rack- and cabinet-style mounting systems.

The modules 16 include any electronics and computing devices available in the art, such as, for example, servers, blades, routers, data storage devices, audio/video equipment, and telecommunications equipment, among others. The modules 16 typically include flanges or ears 22 coupled to opposite sides thereof that couple to members of the mounting frame 14 and suspend the module 16 therebetween. The modules 16 might alternatively be mounted using slides, rails, shelving, or other means known in the art.

The chilled-air duct 10 comprises a base 23, an outer sidewall 24, an inner sidewall 26, a front wall 28, a top wall 30, a rear wall 32 and a vent 34. The duct 10 is dimensioned to be adaptable or retrofitted to an existing rack 12, however the duct 10 can be dimensioned as necessary for a particular application. The width of the duct 10 between the outer and inner sidewalls 24, 26 is configured to enable the duct 10 to fit alongside the rack 12 and/or between adjacent racks 12. In a cabinet-style rack 12 the width of the duct 10 is configured to enable the duct 10 to be disposed between an exterior wall of the cabinet and the mounting frame 14 within the cabinet. The length of the base 23 of the duct 10 between the front and rear walls 28, 32 is also configured to fit within the length of a respective side of the rack 12. The duct 10 can fit between members of the external frame 20 of the rack 12 or can be disposed alongside the external frame 20.

The height of the duct 10 between the surface 64 and the top wall 30 is approximately equal to the height of the highest mounting location for a module 16 in the mounting frame 14 of the rack 12. However, the duct 10 can be configured with any desired height. Similarly, the vent 34 extends substantially between the surface 64 and the top wall 30 and thus has a height that is equal to or just less than that of the duct 10.

The base 23 of the duct 10 is formed by a flange 62 extending from bottom edges of one or more of the outer and inner sidewalls 24, 26, the front wall 28, and the rear wall 32 and generally transversely thereto. The flange 62 can be continuous around the base 23 of the duct 10 or may only be included along one or more portions of the base 23, e.g. only along the bottom edges of the outer and inner sidewalls 24, 26. The base 23 is configured to support the duct 10 on a surface 64, such as a raised floor with an under floor plenum space 66. The interior of the base 23 and thus the duct 10 is open to receive chilled air from beneath the surface 64, e.g. from the plenum space 66, via an opening in the surface over which the base 23 is disposed. The duct 10 rests on top of the surface 62 or the duct 10 can include one or more flanges 68 that extend into and/or through an opening 70 in the surface, as depicted in FIG. 10F. The flanges 70 can aid to support the duct 10 and/or to direct chilled air into the duct 10 from the under floor plenum space 66.

The outer sidewall 24 is parallel to and spaced apart from the inner sidewall 26 with the top wall 30 and the rear wall 30 extending between the uppermost edges thereof. The front wall 28 extends generally transversely from a front edge of the outer sidewall 24. A bottom portion 35 of the front wall 28 may be cut out and adapted for mounting around members of the external frame 20 or mounting frame 14 of the rack 12. The front edge of the inner sidewall 26 is spaced apart from the front wall 28 to provide the vent 34.

The rear wall 32 extends between rear edges of the outer and inner sidewalls 24, 26. The rear wall 32 is angled to slope toward the front wall 28 as the rear wall 32 extends from the base 23 of the duct 10 to the top wall 30. The rear wall 32 provides the duct 10 with a generally right triangular side profile with its uppermost and rearmost apexes truncated. In other embodiments, one or both of the apexes may not be truncated. As depicted in FIGS. 10D-E, the rear wall 32 might follow a curvilinear (FIG. 10C) or non-linear (FIG. 10D) path as it slopes toward the front wall 28. As such, the path of the rear wall 32 may be configured to tailor the flow of chilled air through the duct 10.

The vent 34 is formed by the front wall 28, a side vent wall 36 and a bottom vent wall 38. The side vent wall 36 extends from the front edge of the inner sidewall 26 in a direction that is generally parallel to the front wall 28 and away from the outer sidewall 24. The front wall 28, side vent wall 36 and bottom vent wall 38 form the vent 34 through which chilled air can be channeled and exhausted from the duct 10. The front wall 28 and side vent wall 36 are oriented transverse to the sidewalls 24, 26 and parallel and evenly spaced apart from one another throughout their entirety. Alternatively, the front wall 28 and side vent wall 36 can remain parallel to one another but follow a non-linear path as they extend away from the sidewalls 24, 26 as depicted in FIG. 10A. Such a non-linear path may aid to navigate around or between members of the mounting frame 14 or external frame 20. The non-linear path might also orient the vent 34 to face in a desired direction. In an alternative embodiment, depicted in FIG. 10B, the side vent wall 36 is omitted and the vent 34 is formed by the front wall 28 and the front edge of the inner sidewall 26.

The spacing between the front wall 28 and side vent wall 36 can be varied or configured to provide a desired airflow through the vent 34, e.g. the spacing might be decreased to increase the flow rate of chilled air leaving the vent. The spacing between the front wall 28 and the side vent wall 36 can be varied along the length of the vent 34 as it extends from the duct 10 or from top to bottom of the duct 10.

As depicted best by FIG. 11A, the vent 34 optionally includes a plurality of cross-pins 40 or other members extending between the front wall 28 and the side vent wall 36 adjacent to their distal edges. The cross-pins 40 protrude through the front wall 28 and the side vent wall 36 to provide pegs 42 on each side of the vent 34. Alternatively, the cross-pins 40 do not protrude through from sides of the vent 34. The cross-pins 40 might alternatively be omitted and the pegs 42 affixed or integrated into the front wall 28 and side vent wall 36. The cross-pins 40 can reinforce the vent 34 and can maintain the spacing between the front wall 28 and side vent wall 36. The pegs 42 comprise generally cylindrical protuberances on the front wall 28 and side vent wall 36 but can take the form of flanges, tabs, or hooks, among others.

The front wall 28 and/or the side vent wall 36 might also include one or more protuberances 46, ridges, detents, or other features that protrude or are raised above the front wall 28 or side vent wall 36, as depicted in FIG. 10C. The protuberances 46 can protrude into the space within the vent 34 or outwardly from the front and vent walls 28, 36. As depicted in FIG. 10C the protuberances can be elongate or can take any shape or form desired.

An air-block 44 can be disposed in or around a vent opening 39 to block the flow of chilled air from the vent opening 39. As depicted in FIGS. 9 and 11A the air-block 44 can comprise a cuboidal form or block that is insertable into the vent opening 39 and retained therein via friction between the air-block 44 and the front and vent walls 28, 36. The air-block 44 can have a selectable length to enable a portion of the vent opening 39 that is blocked by the air-block 44 to be customized. In an embodiment, the air-block 44 is cut to a desired length to customize the blocking of airflow from the vent opening 39. The air-block 44 can include a lip 48 or flange that engages an edge of the front wall 28 or the side vent wall 36 to prevent over insertion of the air-block 44 into the vent 34.

In another embodiment, an air-block 44 a, depicted in FIG. 11B, includes a recessed channel 50 extending along its length. The channel 50 is configured to receive the protuberance 46 protruding from the interior of the front and side vent walls 28, 36 depicted in FIG. 10C, and to maintain a desired position of the air-block 44 a along the vent opening 39.

Alternatively, an air-block 44 b might be configured as a c-shaped channel configured to receive the vent 34 therein and to frictionally engage the exterior surface of the front and side vent walls 28, 36. Frictional elements 52 can be provided on an interior surface of the c-shaped channel to aid frictional engagement with the vent 34. In an further embodiment, an air-block 44 c is configured as a c-shaped channel or other member having one or more slots 54 or other receptacle disposed therein for receiving the pegs 42 and/or the cross-pins 40 disposed in the vent 34 as depicted in FIGS. 10A and 11D. The air-block 44 c can be configured to fit within the vent opening 39 and/or to fit around the vent 34 by receiving the front and side vent walls 28, 36 within the air-block 44 c. As such, the slots 54 can engage the pegs 42 exterior to the vent opening 39 or can engage the cross-pins 40 within the vent opening 39. With continued reference to FIGS. 1-9, installation and operation of the chilled-air duct 10 is described in accordance with an embodiment of the invention. Initially, an opening is formed in the surface 64 adjacent a rack 12 to be cooled by the duct 10, such as by cutting floor tiles to provide access to pressurized, chilled air beneath the surface 64. The opening preferably has dimensions generally equal to that of the interior of the duct 10 at the base 23. The duct 10 is placed on the surface 64 over the opening. A foam, rubber, or similar gasket 56, silicon, caulk, or similar sealing element can be provided between the flange 62 on the base 23 and the surface 64 to prevent chilled air from escaping between the duct 10 and the surface 64.

The vent 34 is positioned to extend in front of the mounting frame 14 to direct the vent opening 39 toward the front faces of modules 16 disposed in the rack 12. The vent 34 may be inserted between the mounting frame 14 and the external frame 20 such that the vent opening 39 is directed between the front faces of the modules 16 and a front panel or door (not shown) on the rack 12.

The duct 10 is freestanding and is supported by the base 23, but the duct 10 can be supported by the mounting frame 14 and/or external frame 20 of the rack 12. The duct 10 can be coupled to the mounting frame 14 and/or external frame 20 for additional support. One or more fasteners can also be provided through the flange 62 to couple the duct 10 to the surface 64.

As depicted in FIG. 8, in operation, the duct 10 receives pressurized, chilled air from beneath the surface 64. The chilled air enters the duct 10 through the base 23 and is directed through the vent 34 toward the modules 16 in the rack 12 as depicted by arrows 76. The chilled air is thus substantially prevented from mixing with warmer air around and in front of the rack 12 and from dispersing into a room in which the rack 12 is located. The majority of the chilled air is also prevented from being wasted by passing around or over the rack 12 and mixing with hot air to be expelled from the room.

The forward sloping configuration of the rear wall 32 aids to at least partially equalize distribution of the chilled air throughout the duct 10 and the flow of the chilled air from the vent 34. The forward sloping of the rear wall 32 directs the generally vertically upward flow of the chilled air from beneath the surface 64 toward the front wall 28. The forward slope also acts to decrease the volume of the duct 10 toward the top of the duct 10 which at least partially compensates for decreasing airflow rates of the chilled air as it moves away from the pressurized plenum space 66. As such, the flow of chilled air from the vent 34 may be generally equalized along the height of the vent 34.

The dimensions of the duct 10 may also aid to equalize and control the flow of chilled air from the vent 34. For example, an intake 74 formed by the interior of the base 23 might be approximately 1.625 inches wide and 35.0 inches long to provide an area of about 56.9 square inches, while the vent opening might be approximately 0.5 inches wide and 76.825 inches tall to provide an area of about 38.4 square inches. In another example, the area of the intake 74 is approximately equal to the area of the vent opening 39, e.g. the intake 74 is approximately 2.0 inches wide and 30.0 inches long, providing an area of about 60.0 square inches, and the vent opening is approximately 0.75 inches wide and 82.0 inches tall, providing an area of about 61.5 square inches. It is understood that these dimensions are exemplary and are not intended to restrict embodiments of the invention. The term “approximately” as used herein is intended to indicate deviations from the exact value by +/−10%, preferably by +/−5% and/or deviations in the form of changes that are insignificant for the function.

Such dimensions may be configured to prevent the duct 10 from overly restricting the flow of chilled air from the plenum space 66. A larger area of the vent 34 may also compensate for restrictions on the chilled-air flow caused by friction between the chilled air and the interior surfaces of the duct 10 and/or caused by routing the chilled air around the front edge of the inner sidewall 26 to enter the vent 34.

Additionally, standard perforated tiles known in the art and employed in raised floors for providing pressurized chilled air from an under-floor plenum space typically have an area of about 153 square inches. As such, the duct 10 can be configured for use with a much smaller intake 74 that that of known perforated tiles, e.g. the duct 10 can have an intake 74 that is 57.0 square inches or about one third the size of a standard perforated tile.

Air-blocks 44 are installed in the vent opening 39 to block the flow of chilled air where not needed, e.g. in locations at which no modules 16 are mounted in the rack 12. The air-blocks 44 can be cut to length to generally match that of the unused mounting locations in the rack 12 or to another length as desired. The air-blocks 44 are then inserted into the vent opening 39 and retained in position by friction or other means as described previously above, e.g. hanging from cross-pins 40 or pegs 42.

Testing of airflow from a standard perforated floor tile known in the art and from chilled-air ducts 10 constructed in accordance with embodiments of the invention depict a marked increase in airflow to components mounted in a rack 12. As depicted in Table 1 below, very little or no airflow is produced from standard perforated tiles at small distances above the tile. As such, the chilled air must be drawn through a front grate or louver on the rack 12 and into the modules 16 mounted therein by fans disposed in the modules 16. Additionally, a significant airflow is found above the rack 12 showing the passage of unused or wasted chilled air over the rack 12 rather than through the rack 12 and modules 16 mounted therein. These test data show the inefficient distribution of chilled air from the standard perforated tile and indicate losses of chilled air over the rack 12 of approximately 40%.

Test data for a small scale test model of a chilled air duct 10 constructed in accordance with embodiments of the invention show airflow rates equal to or greater than twice the maximum airflow rate found with the perforated tile throughout the height of the duct 10. Test data from a full scale test model of the chilled air duct 10 show a minimum chilled-air flow rate that is substantially greater than the maximum flow from the perforated tile and an average flow rate that is greater than 320% higher than that from the perforated tile. This increased airflow is also superior to that of the perforated tile because the flow of chilled air is supplied directly to the front of the modules 16 in the rack 12. The chilled air can thus be drawn directly into the modules 16 for cooling; the chilled air is not drawn through grates or louvers on the front of the rack 12. Additionally, both the small scale and full scale tests indicate no flow of chilled air over the rack 12, e.g. no chilled air is lost or wasted over the rack 12.

TABLE 1 Comparison of Perforated Tile and Exemplary Chilled-Air Ducts Small Scale Duct Full Scale Duct % Total Perforated Tile Airflow - measured Airflow - measured Height Airflow (miles 3 inches from vent 3 inches from vent Above Floor per hour) (miles per hour) (miles per hour) 10% 1.8 1.9 2.1 25% 0 4.2 5.9* 50% — 3.6 5.9* 75% 0 3.8 5.9* 100%  — 3.6 5.9* Over Rack 1.1 0.0 0.0 *Average of airflow rate measurements from 25 to 100% of height above floor

Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the scope of the claims below. Embodiments of the technology have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to readers of this disclosure after and because of reading it. Alternative means of implementing the aforementioned can be completed without departing from the scope of the claims below. Certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims. 

What is claimed is:
 1. A chilled-air duct for cooling electronics modules in a rack-mounting system, the chilled-air duct comprising: a first sidewall having a first base dimension and a first top dimension, the first base dimension being greater than the first top dimension; a second sidewall that is parallel to and spaced apart from the first sidewall, the second sidewall having a second base dimension and a second top dimension, the second base dimension being greater than the second top dimension; a front wall coupled to the first sidewall and extending transversely to the first sidewall in a direction toward a plane of the second sidewall, a front edge of the second sidewall being spaced apart from the front wall to form a gap through which chilled air flowing through the duct is exhausted; and a rear wall extending between the first and second sidewalls.
 2. The chilled-air duct of claim 1, further comprising: a vent wall coupled to the front edge of the second sidewall and extending parallel to the front wall and away from the first sidewall, at least a portion of the front wall and the vent wall forming a vent that directs chilled air flowing through the duct toward a space adjacent a front face of an electronic module mounted in the rack-mounting system, the duct being disposed alongside the rack-mounting system.
 3. The chilled-air duct of claim 2, wherein the vent extends from the first and second sidewalls and around at least on support member of the rack-mounting system a sufficient distance to exhaust chilled air flowing through the duct in front of the front face of the electronic module.
 4. The chilled-air duct of claim 1, further comprising: a flange extending from a base of one or more of the first and second sidewalls, the front wall, and the rear wall, the flange supporting the duct on a surface.
 5. The chilled-air duct of claim 4, further comprising: a sealing member disposed between the flange and the surface that prevents chilled air from passing between the duct and the surface.
 6. The chilled-air duct of claim 1, wherein the duct is disposed over an aperture in a surface to receive chilled air from beneath the surface.
 7. The chilled-air duct of claim 2, further comprising: an air-block configured to couple to the chilled-air duct to extend between distal edges of the front wall and vent wall to block the flow of chilled air through at least a portion of the vent.
 8. The chilled-air duct of claim 7, wherein the air-block frictionally engages one or more of the front wall and the vent wall to maintain a position of the air-block on the chilled-air duct.
 9. The chilled-air duct of claim 7, wherein the length of the air-block is configurable to customize the flow of chilled air from the chilled-air duct based on locations of electronics modules disposed in the mounting assembly.
 10. The chilled-air duct of claim 1, wherein at least a portion of the rear wall slopes toward the front wall, and wherein a profile of the chilled-air duct aids to at least partially equalize the flow of chilled air along the length of the gap.
 11. An electronics cabinet with an integral chilled-air duct, the cabinet comprising: a housing formed from a pair of side panels, a top panel, and a front panel extending between the pair of side panels; a mounting frame disposed within the housing and configured to receive a plurality of electronics modules in a vertically stacked orientation; a chilled air duct disposed between a side of the mounting frame and an adjacent one of the pair of side panels of the housing, the chilled air duct having a base and a top wall extending from a front wall that is adjacent a front side of the mounting frame, the base having a length greater than that of the top wall, the top wall being disposed adjacent a top of the mounting frame, and a vent extending between the base and the top wall and directed toward a space between a front of the mounting frame and the front panel.
 12. The electronics cabinet of claim 11, wherein the base of the chilled-air duct rests on a surface and over an opening in the surface and receives chilled air from beneath the surface.
 13. The electronics cabinet of claim 11, wherein the chilled-air duct includes a rear wall extending between the base and the top wall, at least a portion of which slopes toward the front wall of the chilled-air duct.
 14. The electronics cabinet of claim 13, wherein a profile of the chilled-air duct formed by the rear wall at least partially equalizes flow of chilled air along the length of the vent.
 15. The electronics cabinet of claim 11, wherein the vent extends substantially parallel to the front wall of the chilled-air duct between the mounting frame and the door of the housing.
 16. The electronics cabinet of claim 11, further comprising: an air-block coupled to the vent to block the flow of chilled air from at least a portion of the vent, the length of the air-block being infinitely selectable to define the portion of the vent.
 17. An electronics rack with a chilled-air duct, the electronics rack comprising: a mounting frame configured to receive a plurality of electronics modules in a vertically stacked orientation; a chilled-air duct disposed adjacent a side of the mounting frame, the chilled air duct receiving chilled air through an opening in a floor on which the chilled-air duct rests and having a front wall disposed forward of a front of the mounting frame, a base and a top wall extending from the front wall, the base having a length greater than that of the top wall, the top wall being disposed adjacent a top of the mounting frame, a vent formed at least partially by the front wall and extending between the base and the top wall, the vent directing chilled air flowing through the chilled-air duct toward a front side of electronics modules disposed in the mounting frame, and a rear wall extending between the base and the top wall, at least a portion of the rear wall sloping toward the front wall to provide the chilled-air duct with a profile that at least partially equalizes flow of chilled air from the vent.
 18. The electronics rack of claim 17, wherein the chilled-air duct is freestanding.
 19. The electronics rack of claim 17, wherein the portion of the rear wall that slopes toward the front wall is linear.
 20. The electronics rack of claim 17, wherein the portion of the rear wall that slopes toward the front wall is curvilinear.
 21. A chilled-air duct for cooling electronics modules in a rack-mounting system, the chilled-air duct comprising: a hollow duct disposed alongside a mounting frame, the mounting frame configured to receive a plurality of electronics modules in a vertically stacked orientation, the duct having a profile that slopes forward from a rear of the mounting frame toward a front of the mounting frame, the duct including a vent extending substantially the height of a forward portion of the duct, wherein the duct receives a flow of chilled air from an under-floor plenum space, routes the flow of chilled air alongside the mounting frame toward the vent, and discharges the chilled air from the vent in front of an electronics module disposed in the mounting frame.
 22. The chilled-air duct of claim 21, further comprising; an air-block coupled to the duct to block the flow of chilled air from at least a portion of the vent, the length of the air-block being infinitely selectable to define the portion of the vent. 